The big news for ASoC in 3.5 is the first two changes here which are pretty major features for the subsystem:

Dynamic PCM support, allowing support for SoCs with internal routing through components with tight sequencing and formatting constraints within their internal paths or where there are multiple components connected with CPU managed DMA controllers inside the SoC.

Greatly improved support for direct digital links between off-SoC devices, providing a much simpler way of connecting things like digital basebands to CODECs.

Much more fine grained and robust locking, cleaning up some of the confusion that crept in with multi-component.